1. Field of the Invention
This invention relates to a locking slide fastener slider of automatic, semi-automatic or manual type, and more particularly to the shape of a locking-pawl-insertion through-hole, which is part of a locking mechanism on a slider body.
2. Description of the Related Art
In some of conventional locking sliders of the automatic, semi-automatic or manual type, a locking-pawl-insertion through-hole in the form of a square slot is located in a central ledge extending on the lower surface of an upper wing from a guide post to the rear end of a guide channel in which a pair of rows of fastener elements is to be guided. And in others of the conventional locking sliders, such locking-pawl-insertion through-hole is located in one of opposite side recesses, one on each side of the central ledge, in the lower surface of the upper wing.
Japanese Utility Model Laid-Open Publication No. Sho 57-7313 discloses a locking slider as shown in FIG. 11 of the accompanying drawings of the present specification. In this slider, a square locking-pawl-insertion through-hole 15' is located about a center of a central ledge 10' on the lower surface of an upper wing 2', and a plate-like locking pawl 21' is automatically inserted into a space between adjacent legs of one of opposed rows of fastener elements being coupled together in a guide channel 6' of a slider body 1' to temporarily stop the sliding of the slider.
U.S. Pat. No. 2,901,803 discloses a locking slider as shown in FIG. 12 of the accompanying drawings of the present specification. In this slider, a rectangular locking-pawl-insertion through-hole 15" is located in one of opposite side recesses 9" at a position toward the rear end of the guide channel 6", off a central ledge 10" on the lower surface of the upper wing 2", and a longitudinally elongated locking pawl 21" is inserted into the locking-pawl-insertion through-hole 15" to automatically press the legs of one of opposed rows of fastener elements being coupled together in the guide channel 6" of a slider body 1", thus temporarily stop the slider.
In either locking slider of the above-named publications, partly since the locking pawl presses the legs of the coupled fastener elements or is inserted into a space between adjacent legs at a position in the central ledge or in the one side recess to automatically stop the sliding of the slider, and partly since the locking-pawl-insertion through-hole is located in a flat area, possible influence on the fastener elements due to the locking-pawl-insertion through-hole would not be very much.
Whereas in the locking slider according to this invention, the locking-pawl-insertion through-hole is located in and across the boundary between the central ledge and one of opposite side recesses in the guide channel. Either of the above-named prior art publications is totally silent about this concept. Still, with a hypothetical combination of the locking-pawl-insertion through-holes of these prior art forms, a squared step was created in the locking-pawl-insertion through-hole at the boundary between the central ledge and the side recess and due to this stepped locking-pawl-insertion through-hole, the frictional resistance of the fastener elements would become large so that smooth sliding of the slider could not be realized and the fastener elements would be damaged by the locking-pawl-insertion through-hole. Having the surfaces of the legs of the fastener elements with scratches, the slide fastener would be unsightly.